Shining insects: Papuan golden stag beetles

Happy New Year! New Year's brings with it auspicious items. Many people have prayed for good fortune with sparkling objects, such as the oval coins of a beckoning cat or the gold flakes floating in toso sake.

The specimens currently on display were bred from a pair of green ones donated by the Hiroshima City Forest Park Conservation Center. Both the male and female parents were green, but the offspring came in a variety of colors, including green, yellow-green, and blue.

Males have large, curved mandibles and axe-shaped protrusions on their front legs.

When you think of stag beetles, you probably imagine them feeding on tree sap, but this stag beetle is a bit unusual; it cuts the stems of grass and other plants and sucks the sap that comes out. The inside of its mandibles have comb-like protrusions that it uses to pinch and hold the plant stem, and it uses the axe-like protrusions like a saw to cut it. The female's front legs do not have protrusions and cannot cut the stem, so the male flies to the cut and gets to the food.

At the zoo, they are fed insect jelly, so they do not cut stems to suck the juices, but they can be observed climbing artificial plants and moving around.

This stag beetle is beautiful and easy to raise, so it is recommended for beginners, but there are some things you should be aware of when raising it.

According to a report on an experiment to see what kind of grass the Papua golden stag beetle cuts, it was confirmed that it cuts the stems of various flowers sold in garden centers. This means that if it escapes into the wild, it could become a pest that would have a major impact on Japan's agriculture and natural environment. Considering the climate of its habitat, Papua New Guinea, it may be difficult for it to survive the Japanese winter outdoors, but there is a risk that it could become established in warmer regions. This may seem obvious, but when raising it, please be very careful not to let it escape into the wild.

In addition to the Papuan golden stag beetle, you can also see other sparkling insects, such as the pupa of Tree Nymph, at the Insectarium of Tama Zoo. Please come and visit us. We look forward to seeing you again in 2026.

[Sasaki, Insectarium Breeding and Exhibit Manager at Tama Zoo]